Antenna arrangement for distributed massive MIMO

ABSTRACT

An antenna arrangement ( 300 ) comprising a body ( 301 ) comprising a plurality of antenna devices ( 315 ), the antenna arrangement being characterized in that the body ( 301 ) having a flexible structure and an elongated shape and wherein the antennas are arranged in a non-orthogonal co-polarized manner.

TECHNICAL FIELD

The present invention relates generally to the field of wirelesscommunication. More particularly, it relates to an improved antennaarrangement for use in massive MIMO (multiple-input and multiple-output)systems, more particularly distributed massive MIMO systems (D-maMIMO ordistributed maMIMO).

BACKGROUND

Massive MIMO is one example of Multi-user MIMO (MU-MIMO) which is a setof multiple-input and multiple-output technologies for wirelesscommunication, in which a set of users or wireless terminals, each withone or more antennas, communicate with each other. In contrast,single-user MIMO considers a single multi-antenna transmittercommunicating with a single multi-antenna receiver. In a similar waythat OFDMA adds multiple access (multi-user) capabilities to OFDM,MU-MIMO adds multiple access (multi-user) capabilities to MIMO. MU-MIMOhas been investigated since the beginning of research into multi-antennacommunication, including work by Telatar on the capacity of the MU-MIMOuplink. Multiple-antenna (MIMO) technology is becoming mature forwireless communications and has been incorporated into wirelessbroadband standards like LTE and Wi-Fi. Basically, the more antennas thetransmitter/receiver is equipped with, the more the possible signalpaths and the better the performance in terms of data rate and linkreliability. The price to pay is increased complexity of the hardware(number of RF amplifier frontends) and the complexity and energyconsumption of the signal processing at both ends.

Massive MIMO (also known as large-scale antenna systems and very largeMIMO) is thus, as stated above, a multi-user MIMO technology where eachbase station (BS) is equipped with a large number of antenna elements(at least 50), which are being used to serve many terminals that sharethe same time and frequency band and are separated in the spatialdomain. A key assumption is that there are many more BS antennas thanterminals; at least twice as many, but ideally as many as possible.Massive MIMO offers many benefits over conventional multi-user MIMO.First, conventional multi-user MIMO is not a scalable technology, sinceit has been designed to support systems with roughly equal numbers ofservice antennas and terminals, and practical implementations typicallyrelies on frequency-division duplex (FDD) operation. By contrast, inmassive MIMO, the large excess of service antennas over active terminalsTDD operation brings large improvements in throughput and radiatedenergy efficiency. These benefits result from the strong spatialmultiplexing achieved by appropriately shaping the signals sent out andreceived by the base station antennas. By applying precoding to allantennas the base station can ensure constructive interference amongsignals at the locations of the intended terminals, and destructivealmost everywhere else. Furthermore, as the number of antennasincreases, the energy can be focused with extreme precision into smallregions in space. Other benefits of massive MIMO include use of simplelow-power components since it relies on simple signal processingtechniques, reduced latency, and robustness against intentional jamming.

By operating in TDD mode, massive MIMO exploits the channel reciprocityproperty, according to which the channel responses are the same in bothuplink and downlink. Channel reciprocity allows the BSs to acquirechannel state information (CSI) from pilot sequences transmitted by theterminals in the uplink, and this CSI is then useful for both the uplinkand the downlink. By virtue of the law of large numbers, the effectivescalar channel gain seen by each terminal is close to a deterministicconstant. This is called channel hardening. Thanks to the channelhardening, the terminals can reliably decode the downlink data usingonly long-term statistical CSI, making most of the physical layercontrol signaling redundant, i.e. low-cost CSI acquisition. This rendersthe conventional resource allocation concepts unnecessary and results ina simplification of the MAC layer. These benefits explain why massiveMIMO has a central position in preliminary 5G discussions.

However, massive MIMO system performances are affected by some limitingfactors: Channel reciprocity requires hardware calibration. In addition,the so called pilot contamination effect is a basic phenomenon whichprofoundly limits the performance of massive MIMO systems.Theoretically, every terminal in a massive MIMO system could be assignedan orthogonal uplink pilot sequence. However, the maximum number oforthogonal pilot sequences that can exist is upper-bounded by the sizeof the coherence interval, which is the product of the coherence timeand coherence bandwidth. Hence, adopting orthogonal pilots leads toinefficient resource allocation as the number of the terminals increasesor it is not physically possible to perform when the coherence intervalis too short. As a consequence, pilots must be reused across cells, oreven within the home cell (for higher cell density). This inevitablycauses interference among terminals which share the same pilot. Pilotcontamination does not vanish as the number of BS antennas grows large,and so it is the one impairment that remains asymptotically.

To implement massive MIMO in wireless networks, two differentarchitectures can be adopted:

Centralized (C-maMIMO) 101, where all the antennas 110 are co-located ina compact area at both the BS 120 and user sides, UEs 115, as shown inFIG. 1 . It represents the conventional massive MIMO system.

Distributed (D-maMIMO) 102, where BS antennas, herein named as accesspoints (APs) 135, are geographically spread out over a large area, in awell-planned or random fashion, as shown in FIG. 2 . Antennas 135 areconnected together and to a central processing unit (CPU) 130 throughhigh-capacity backhaul links 140 (e.g. fiber-optic cables). It is alsoknown as cell-free massive MIMO system.

The inventors believe that D-maMIMO architecture is one importantenabler of network MIMO in future standards. Network MIMO is aterminology that is used for a cell-free wireless network, where all theBSs that are deployed over the coverage area act as a single BS withdistributed antennas. This can be considered the ideal networkinfrastructure from a performance perspective, since the network hasgreat abilities to spatially multiplex users and exactly control theinterference that is caused to everyone.

The distinction between D-maMIMO and conventional distributed MIMO isthe number of antennas involved in coherently serving a given user. InD-maMIMO, every antenna serves every user. Compared to C-maMIMO,D-maMIMO has the potential to improve both the network coverage and theenergy efficiency, due to increased macro-diversity gain. This comes atthe price of higher backhaul requirements and the need for distributedsignal processing. In D-maMIMO, the information regarding payload data,and power control coefficients, is exchanged via the backhaul networkbetween the APs and the CPU. There is no exchange of instantaneous CSIamong the APs or the central unit, that is CSI acquisition can beperformed locally at each AP.

Due to network topology, D-maMIMO suffers from different degrees of pathlosses caused by different access distances to different distributedantennas, and very different shadowing phenomena that are notnecessarily better (antennas deployed at the street level are moreeasily blocked by buildings than antennas deployed at elevatedlocations). Moreover, since the location of antennas in D-maMIMO has asignificant effect on the system performance, optimization of theantenna locations is crucial. In addition, D-maMIMO potentially systemsuffers a low degree of channel hardening. As mentioned earlier, thechannel hardening property is key in massive MIMO to suppresssmall-scale fading, and derives from the huge number of antennasinvolved in a coherent transmission. In D-maMIMO, APs are distributedover a wide area, and many APs are very far from a given user.Therefore, each user is effectively served by a smaller number of APs.As a result, channel hardening might be less pronounced. This wouldconsiderably affect the system performance.

The performance of any wireless network is clearly the availability ofgood enough CSI to facilitate phase-coherent processing at multipleantennas. Intuitively, acquiring high quality CSI should be easier witha C-maMIMO than in a D-maMIMO where the antennas are distributed over alarge geographical area. Nevertheless, the macro-diversity gain has adominant importance and leads to improved coverage and energyefficiency.

A problem with a massive MIMO deployment is that a large number ofantennas generate a large amount of data. This implies that withtraditional radio to antenna interfaces very large capacity fibernetwork are needed to shuffle this data around. Fiber is both expensiveand needs skilled personal for installation. Both of which limit thedeployment scenarios for massive MIMO. There is also a scalability issueas different size base-band units are needed to handle different arraysizes, e.g. one to handle 32 antennas one other for 128 antennas etc.

From a practical point of view, C-maMIMO solution where all antennaelements (i.e., APs) are placed close together has a number of drawbackscompared to D-maMIMO solution where the antenna elements are distributedover a larger area. These are e.g.

-   -   Very large service variations: UEs that happen to be located        close to the central massive MIMO node will experience very good        service quality while for UEs further away the service quality        will degrade rapidly.    -   Sensitive to blocking: On high frequency bands in particular the        signal is easily blocked by obstacles that obscures the        line-of-sight between the UE and the C-maMIMO node. In D-maMIMO        a number of antenna elements may be blocked but it requires much        larger obstacles to block all antenna elements    -   High heat concentration: Due to heat concentration it is        difficult to make C-maMIMO nodes very small. In D-ma MIMO each        antenna element (and its associated processing) generates only a        small amount of heat and this simplifies miniaturization.    -   Large and visible installations: C-maMIMO installations can        become large, especially on lower frequency bands. D-maMIMO        installations are actually even larger, but the visual impact        can be made almost negligible.    -   Installation requires personnel with “radio skills”: Installing        a complex piece of hardware in a single location requires        planning and most probably also proper installation by certified        personnel. In a D-maMIMO installation it is less crucial that        each and every one of the very many antenna elements are        installed in a very good location. It is sufficient that the        majority of the elements are installed in good enough locations.        The requirements on installation can be significantly relaxed        with a D-maMIMO deployment.    -   Power limited by regulations (e.g. specific absorption rate        SAR): If the antenna elements are located close together there        will be an area close to the installation where electromagnetic        wave safety rules applies. This is likely to put limits on the        total radiated radio frequency power in many installations. In a        D-maMIMO installation a user may come close to a small number of        antenna elements but it is impossible to be physically close to        many elements that are distributed over a large area.

There are many significant benefits with D-maMIMO compared to C-maMIMO.But the cabling and internal communication between antenna elements in aD-maMIMO is prohibiting in state-of-the art solutions. It is noteconomically feasible to connect a separate cable between each antennaelement and a central processing unit (e.g. in a star topology) in aD-maMIMO installation. Both a arbitrary and a optimal AP topology ontheir own may lead to a prohibitive cost for the backhaul component, aswell as installation cost for distributing processing and settings.

There is thus a need to provide a distributed maMIMO system that is easyand cheaper to install.

There is also a need for an improved processing and internalcommunication between individual antenna elements and a centralprocessing unit in any MIMO installation, i.e., regardless if it iscentralized or distributed and regardless if the number of antennaelements in the MIMO installation is large or small.

SUMMARY

It should be emphasized that the term “comprises/comprising” when usedin this specification is taken to specify the presence of statedfeatures, integers, steps, or components, but does not preclude thepresence or addition of one or more other features, integers, steps,components, or groups thereof.

It is an object of some embodiments to solve or mitigate at least someof the above or other disadvantages.

This is generally achieved by providing a base station (BS) base stationcharacterized by that antenna elements and the associated antennaprocessing hardware are located inside the same cable that provides datatransfer and power supply to said antenna elements and processinghardware.

According to a first aspect, this is achieved by an antenna arrangementfor a base station to be used in a Distributed maMIMO system comprisinga body comprising a plurality of antenna devices, the antennaarrangement being characterized in that the body having a flexiblestructure and an elongated shape.

In some embodiments, the antenna arrangement may further comprise aconnector (700) for connecting the antenna arrangement to a central unit(610), acting as a base station.

In some embodiments, the antenna arrangement may further comprise a busportion and a power supply line for transmitting data to and from theplurality of antenna devices and/or to/from the central unit.

In one embodiment the bus portion and the power supply line are the sameconnection.

In some embodiments each antenna device comprises a controller and anantenna element, wherein said controller is configured for performingper element processing, the antenna arrangement thus being arranged fordistributed processing utilizing the controllers of the antenna devices.

In some embodiments, the antenna arrangement may further comprise or maybe arranged to be connected to a connector for connecting the antennaarrangement to at least one other antenna arrangement.

In some embodiments, the antenna arrangement may further comprise or maybe arranged to be connected to a power unit.

In some embodiments the antenna devices are arranged in one row.

In some embodiments a majority of the antenna devices, such as all, arearranged to face the same direction.

In some embodiments the antenna devices are arranged in a cover orsheath of said body. In some embodiments the body is a cable.

In some embodiments the body is an elongated strip.

In some embodiments the body is a film.

In some embodiments, additional devices such as additional sensors maybe integrated in the antenna arrangement: for example. Temperaturesensor, Pressure sensor, Light sensor, Proximity sensor, Vibrationsensor, Microphones, Camera sensors, Malfunction detection or alarms,such as e.g. burglar alarm.

According to a second aspect there is provided distributed massive MIMO(Multiple Input Multiple Output System) comprising a central unitarranged to act as a base station and at least one antenna arrangementaccording to above.

An advantage of some embodiments is that a cost efficient buildingpractice for distributed Ma-MIMO base stations is provided.

The present invention also provides for simple and accurate positioning.

The present invention also removes the requirement of an advanced timingor angular estimation.

As is known, the radio frequency waves, being electromagnetic waves,propagate from (and to) an antenna in a given polarization plane. Theefficiency at which a signal is received thus depend on at which anglethe receiver is being held in relation to the sender. To enable for amore uniform reception that is relatively insensitive to the angle ordirection that a device is being held at, common practice has become totransmit signals as cross-polarized signals. This requires that twoantennas are arranged substantially orthogonally and transmitting thesame signal. A signal will then always be received at an acceptablesignal strength level irrespective the angle of the receiver.

The inventors have realized, after inventive and insightful reasoning,that, by going against this fundamental principle in radio frequencytransmissions, a smaller and more flexible antenna arrangement may beachieved.

It is an object of some embodiments to solve or mitigate at least someof these disadvantages associated with the prior art antennas asdiscussed herein.

This is generally achieved by providing a base station (BS) base stationcharacterized by that antenna elements comprising antenna pairs, whereinthe antenna pairs are arranged non-orthogonally.

According to a first aspect, this is achieved by an antenna arrangementfor a base station to be used in a Distributed maMIMO system comprisinga body comprising a plurality of antenna devices, each antenna devicecomprising an antenna pair arranged in a crossing manner, the antennaarrangement being characterized in that the body having a flexiblestructure and an elongated shape and the antennas in the antenna pairsare arranged non-orthogonally.

In one embodiment, the antenna pairs are arranged non-orthogonally bybeing arranged at angles not being straight with relation to oneanother.

This reduces the width needed for an antenna pair and may enable anantenna arrangement to have a narrower shape.

In one embodiment, the antenna pairs are arranged non-orthogonally bybeing at least one of the antennas of an antenna pair being arranged ina bent or not straight form.

This reduces the width needed for an antenna pair and may enable anantenna arrangement to have a narrower shape.

In one embodiment, the antenna arrangement comprises at least twoantenna pairs, where the antenna pairs are arranged so that the polarityof one antenna pair is opposite the polarity of the adjacent antennapair. This increases the compensation for the reduced effect of cross-ordual-polarisation.

By not requiring “perfect orthogonality” between antenna polarizationbranches of a distributed massive MIMO antenna (radio stripe) the widthof the radio stripe can be made smaller. Reducing the stripe widthgreatly simplifies the installation, the cost, and handling of the radiostripes. The loss in performance can partly be compensated for in twoways:

1. By introducing more antenna elements; and/or

2. By applying slightly more advanced algorithms compensating fordegradations (e.g. interference reducing MIMO receivers,interference-aware beam-forming, etc).

BRIEF DESCRIPTION OF THE DRAWINGS

Further objects, features and advantages will appear from the followingdetailed description of embodiments, with reference being made to theaccompanying drawings, in which:

FIG. 1 is a schematic drawing illustrating an example prior artcentralized maMIMO system;

FIG. 2 is a schematic drawing illustrating an example prior artdistributed maMIMO system;

FIG. 3 is a schematic illustration of an antenna arrangement accordingto one embodiment of the present invention;

FIG. 4A shows a schematic side view of a variation of an antennaarrangement according to an embodiment of the present invention;

FIG. 4B shows a schematic side view of a variation of an antennaarrangement according to an embodiment of the present invention;

FIGS. 5A to 5C show various examples of placements of antennaarrangements;

FIG. 6 shows an example of a system configured to utilize antennaarrangements according to embodiment of the present invention;

FIG. 7 shows a general concept of connecting several antennaarrangements in series and in parallel;

FIG. 8 shows a schematic view of an example embodiment of the presentinvention;

FIG. 9 shows a schematic view of a UE communicating with antenna devicesaccording to an example embodiment of the present invention;

FIG. 10 shows a general method for executing the processing illustratedin FIG. 9 according to an example embodiment of the present invention;

FIG. 11 shows a serialized transmission TX interface of Massive-MIMOtransmission according to an example embodiment of the presentinvention;

FIG. 12 shows a serialized reception RX interface for Massive-MIMOreception according to an example embodiment of the present invention;

FIG. 13 shows a flowchart for performing the method of performingper-element processing according to an example embodiment of the presentinvention;

FIG. 14 shows an example of batch receiver processing according to anexample embodiment of the present invention;

FIG. 15 , shows an example of a configuration of reference signal forreciprocity based transmission according to an example embodiment of thepresent invention;

FIG. 16 shows an example of a configuration of reception of an ULtransmission according to an example embodiment of the presentinvention;

FIG. 17 shows the 10th percentile, median and 90th percentile of theper-user achievable downlink rates, for different values of a accordingto an example embodiment of the present invention;

FIG. 18 shows an example embodiment of the present invention;

FIG. 19 shows an example embodiment of the present invention; and

FIG. 20 shows an example embodiment of an antenna pair according to oneexample of the present invention;

FIG. 21 shows an example embodiment of an antenna arrangement accordingto one example of the present invention;

FIG. 22 shows an example embodiment of an antenna arrangement accordingto one example of the present invention;

FIG. 23 shows an example embodiment of an antenna pair according to oneexample of the present invention;

FIG. 24 shows an example embodiment of an antenna arrangement accordingto one example of the present invention; and

FIG. 25 shows an example embodiment of an antenna arrangement accordingto one example of the present invention.

DETAILED DESCRIPTION

In the following, embodiments will be described where an antennaarrangement being flexible is used to provide a distributed maMIMOsystem 100.

FIG. 3 is a schematic illustration of an antenna arrangement accordingto one embodiment of the present invention. The antenna arrangement 300comprises a cable 301 having a sheath or cover 305 encompassing a centrecore 310. As would be understood by a skilled person, the cover orsheath may comprise a jacket and/or an insulating shield, being ametallic shield or a dielectric insulator depending on the type of core.Such elements are not shown to maintain the schematic illustrationuncluttered and easily understandable. Such elements are taken to becomprised in the cover.

As can be seen in the figure, the antenna arrangement 300 comprises aplurality of antenna devices 315. The number of antenna devices 315 inone antenna arrangement varies with the intended frequency and thelength of the antenna arrangement 300, but one example is a 100 meterlong cable 301 housing 400 antenna devices 315.

In one embodiment, the antenna devices 315 are encased in the cover 305.In one embodiment, the antenna devices 315 are housed in the cover 305.As a skilled person would understand, there exist several options of howto provide the antenna devices 315 in the cover 305 of the antennaarrangement 300, housing or encasing being but two options.

In one embodiment, the core 310 comprises a bus portion 311 fortransmitting information and data. In one embodiment, the bus portion311 comprises a metal-based cable 311 for transmitting information anddata. No difference will be made between data and information for thepurposes of this application and they will both be referred to asinformation or data interchangably. In one embodiment, the bus portion311 comprises an optical fibre for transmitting information and databetween the antenna devices 315 and a processing unit (not shown in FIG.3 ).

The antenna device 315 comprises a data port 313 for transmittinginformation and data to/from other antenna devices 315 and/or theprocessing unit through the bus portion 311.

In one embodiment, the core 310 also comprises a power supply line 312for providing the antenna devices 315 with power. The antenna device 315comprises a coupling 314 for receiving power from the power supply line312.

In one embodiment, each antenna device 315 requires 2 W of power forhandling all processing and providing 0.1 W Radio Frequency outputpower. IN an antenna arrangement with 100 elements, this results in aradio output of 10 W for a total power consumption of 200 W.

As larger number of antenna devices are most likely needed, the overallneeded power will grow and placing all antennas in close proximity toone another, as in prior art systems provides for problems when it comesto heat dissipation. But, by arranging all elements in stripes as perthe present invention, the antenna devices are spread over a larger areaand at a larger distance from one another, thus solving the problem ofheat dissipation.

In one embodiment, where the bus portion 311 is capable of transmittingpower, the bus portion 311 and the power supply line 312 may be one andthe same element 311/312. In one such embodiment, the power coupling 314and the data port 313 may be the same connection 313/314.

In one such embodiment, the data is transmitted along with the power bysuperimposing the information on the current.

As can be seen in FIG. 3 , one antenna device is shown in an enlargedschematic view, showing some components of the antenna device 315. Theantenna device 315 comprises a controller such as a processor or CentralProcessing Unit, CPU with accompanying memory (not explicitly shown, buttaken to be comprised in the controller, even if different from theprocessor) for storing instructions and data.

The antenna device also comprises a Power Unit (PU) arranged to receiveand distribute power as needed by the various components. The Power Unit(PU) may also act as the data port for receiving data being transmittedalong with the power.

The antenna device 315 also comprise at least one antenna element ANT.The size of the antenna element depends on the frequency that theantenna is designed to operate at. For example, a frequency of 60 GHzrequires that the antenna element is at least 5 mm, 30 GHz requires thatthe antenna element is at least 20 mm; 15 GHz requires that the antennaelement is at least 40 mm and 2 GHz requires that the antenna element isat least 75 mm.

As can be seen in FIG. 3 , the antenna arrangement 300 is housed in acable 301 having a round form. However, this is only an exampleembodiment, and several other options exist, as will be shown in FIGS.4A and 4B.

FIG. 4A shows a schematic side view of a variation of an antennaarrangement according to an embodiment of the present invention. As canbe seen in FIG. 4A, the antenna arrangement comprises an elongated body301 comprising a cover 305 housing a plurality of antenna devices 315(only one seen) which are connected to a power supply line 312 through acoupling 314 and a bus portion 311 through a data port 313.

The elongated body 301 has a length that far exceeds the width at leastby a factor of 50. In one embodiment the length exceeds the width by afactor 100. In one embodiment the length exceeds the width by a factor500. In one embodiment the length exceeds the width by a factor 1000.The width thus, in some embodiments, practically being negligiblecompared to the length.

The height of the body 301 is considered to be in the same order as thewidth, or smaller than the width, in some embodiments practically beingnegligible compared to the length.

The antenna arrangement may comprise an adhesive layer 306 forsimplifying the mounting of the antenna arrangement 300 to a structuresuch as a wall or ceiling or roof.

FIG. 4B shows a schematic side view of a variation of an antennaarrangement according to an embodiment of the present invention. As canbe seen in FIG. 4B, the antenna arrangement comprises a wide elongatedbody 301, such as a film comprising a cover 305 housing a plurality ofantenna devices 315 a, 315 b and 315 c. In FIG. 4B only three antennadevices are shown, but it should be noted that as this is a side view,the shown antenna devices 315 a-c represent rows of antenna devices. Theantenna devices 315 in a row may be supplied by a designated (designatedfor that row) power supply line 312 and bus portion 311 as for antennadevice 315 a. The antenna devices 315 in a row may alternatively oradditionally be supplied by a shared power supply line 312 and busportion 311 as for antenna devices 315 b and 31 cb.

The antenna arrangement may comprise an adhesive layer 306 forsimplifying the mounting of the antenna arrangement 300 to a structuresuch as a wall or ceiling or roof.

The exact shape of the antenna arrangement is not at the core of thepresent invention, but that the antenna arrangement has an elongatedform is as this provides for a distributed placing of antenna device315.

The antenna arrangement 300 is preferably flexible, at least in themanner that it is able to be rolled on a spool. In one embodiment theantenna arrangement 300 is flexible in the manner that it can be bent inat least one degree of freedom (such as up/down with reference to FIG. 4). In one embodiment the antenna arrangement 300 is flexible in themanner that it can be bent in at least two degrees of freedom (such asup/down and left/right with reference to FIG. 4 ).

This may be accomplished by constructing the cover 305 of the antennaarrangement 300 of a flexible material and by spacing the antenna device315 sufficiently for allowing a degree of bending. The exact spacingrequired depends on the size of the antenna device 315 and the desireddegree of flexibility, and also the shape of the sheath 305.

By providing an elongated and flexible antenna arrangement severalbenefits are achieved.

One benefit is that the antennas may be distributed in a more freemanner by simply deploying the antenna arrangement 300. As the data busand the power supply is included in the arrangement, there is no needfor difficult installation procedures requiring knowledge in radiotechnology.

Another benefit is that the antenna arrangement becomes apparentlysmaller as it may be distributed in a more clever manner, such as byfollowing contours of a building instead of being placed as a largepanel on the top of the building.

Another benefit is that the antenna arrangement may be arranged orplaced around corners of a building thereby avoiding many so calledblocking issues that may arise in urban installations where buildings(even the one the antenna is placed on) may block the radio waves sentor received by the antenna(s). By providing a flexible antennaarrangement, the antenna arrangement may be draped around cornersthereby receiving a free field of view for transmitting signals.

As the antenna arrangement may be placed in an irregular manner and overa larger area, the likelihood that all possible fields of view arecovered increases dramatically, and the entire view around the antennaarrangement (or most of it) may be serviced by at least some antennas.This provides for a reduced requirement for precision installations, andagain, the antenna arrangement is much easier to install.

The embodiments of FIGS. 3 and 4A show antenna arrangements where allantenna devices are connected in a row, for example in series, butparallel connections may also be used, as long as the antenna devicesare arranged substantially in a row. The row does not need to be astraight line, but a general row will suffice for providing additionalflexibility in all directions. Such embodiments are also easy to installas they are highly flexible to work with unlike broad and/or rigidarrangements, as in the prior art.

The embodiments of FIGS. 3, 4A and 4B show antenna arrangements whereall antenna devices are arranged to face the same general direction.However, it is possible to arrange the antenna devices also facingdifferent directions (to simplify installing as the installer does notneed to place the antenna arrangement in any particular direction, theembodiment where all or most antenna elements face the same generaldirection (assuming the strip is placed in a straight line) carries thebenefit that all antenna devices are put to use, it will be easy toinstall as the direction of the antenna devices can easily be marked andall antenna devices are facing the same direction thereby ensuring thatone knows which area is covered. Should more or additional areas/angleswant to be covered this is easily achieved by the antenna arrangementbeing arranged in a different shape, the antenna arrangement beingflexible thus allowing this.

Additionally, the flexibility also allows for a high precisioninstallation as the antenna arrangement may be formed (to a degree) tofit the surroundings. FIGS. 5A to 5C show various examples of placementsof antenna arrangements 300, the antenna arrangements 300 beingindicated by dotted lines. In FIG. 5A an example of placing the antennaarrangements according to herein along structure lines of a shoppingmall is shown. This will enable all customers, staff and also(stationary) equipment in the shopping mall to be serviced efficientlyin all areas/corners of the shopping mall in manner where the actualantennas are hidden or at least not given a prominent position so thatthe visitors might not even notice the massive arrangement of antennas.

In FIG. 5B an example of placing the antenna arrangements according toherein along structure lines of an airport is shown. This will enableall travelers, staff and also (stationary) equipment in the airport tobe serviced efficiently in all areas/corners of the airport in mannerwhere the actual antennas are hidden or at least not given a prominentposition so that the visitors might not even notice the massivearrangement of antennas. As this is in an airport assumingly receiving alot of foreign user equipments, this also allows for placing additionalantenna arrangements should such be needed to provide service for usershaving foreign or unusual telecommunication needs, such as operatingunder different frequencies. This would not be possible using largepanels as the panels would simply take too much space, space which isneeded for information or advertising purposes.

In FIG. 5C an example of placing the antenna arrangements according toherein along structure lines of a sports stadium is shown. This willenable all visitors and also stationary equipment in the sports stadiumto be serviced efficiently in all areas/corners of the sports stadium inmanner where the actual antennas are hidden or at least not given aprominent position so that the visitors might not even notice themassive arrangement of antennas. This also allows for placing a largenumber of antennas servicing an assumingly large number of visitors(over 40.000 visitors is not uncommon and some stadiums may even houseover 100.000 visitors, with some examples having been known of over200.000 visitors—Strahov Stadium) in one small area. This would not bepossible using large panels as the large panels would require too muchspace, special mountings which may be too heavy for existing structures,and might even block the view of the sports field.

FIG. 6 shows an example of a system 600 configured to utilize antennaarrangements 300 according to embodiment(s) disclosed herein.

A central (processing) unit 610 is connected to a plurality of antennaarrangements 300 each comprising a plurality of antenna elements (notreferenced but indicated by the dots). The central unit 610 or basestation, is thus enabled to service a plurality of user equipments (UEs)115.

As can be seen in FIG. 6 , the antenna arrangements may be placed instraight lines to provide for a structured arrangement. The antennaarrangements may also or alternatively be placed in curved lines toprovide for a flexible arrangement, such as around a house or otherbuilding or structure.

As can also be seen in FIG. 6 , the central unit 610 may also beconnected to an access point or antenna panel 620. The antennaarrangement according to herein is thus possible to combine with priorart antenna panels.

The antenna arrangement 300 naturally comprise a connector at one endfor being connected to the central unit. However, the antennaarrangement may also comprise two connectors, one at each end forconnecting to further antenna arrangements. This enables for placing theantenna arrangements in series. As can also be seen in FIG. 6 , theantenna arrangement may also be spliced or connected in parallel throughthe connectors, possibly through a multiple way connector.

The exact structure of such connectors depend on the type of busportion, power supply line and shape of the antenna arrangement, but asconnectors are generally known, no specific details will be given as tothe structure of the connector. However, FIG. 7 shows the generalconcept of connecting several antenna arrangements in series and inparallel. The upper portion of FIG. 7 shows a serial connection betweena first antenna arrangement 300 a, a second antenna arrangement 300 band a third antenna arrangement 300 c through a connector 700 a. Thelower portion of FIG. 7 shows a serial connection between a firstantenna arrangement 300 a and a second antenna arrangement 300 b througha connector 700 b.

To provide enough power for all antenna elements 300, it may benecessary to include intermediate power units that are to be connectedin series (or parallel) with the antenna arrangements 300. In oneembodiment a connector 700 may comprise a power unit 710. The power unit710 may be battery powered, arranged to be connected to a power outlet,or be solar powered.

This allows for many antenna arrangements to be connected, which in turnprovides for each antenna arrangement to be of a small size, therebybeing easier to transport and handle to and at an installation site.

In one embodiment, as shown in FIG. 8 showing a schematic view of anexample embodiment of the present invention, the antenna arrangement 300is further arranged to comprise at least one additional device 810. Inthe example of FIG. 8 , two such sensors 810 a, 810 b are shown as beinginterspersed between the antenna devices 315, but it should be notedthat the number of additional devices 810 and their placement relativethe antenna devices may vary from embodiment to embodiment.

The additional devices 810 may be alarms, error detection devices and/orsensors such as temperature sensors, microphones, pressure sensors,vibration sensors, optical sensors, such as ambient light sensors orcameras, to mention a few examples.

The sensors 810 may be connected to the power supply line 312 and thebus portion 311 as are the antenna devices 315. This provides for a widearray of sensors or other devices to be distributed over an area,wherein their power supply and the communication with the devices arealready handled by the antenna arrangement 300.

Examples of how to use such additional devices may be to employvibration sensors for collecting vibration information over a largearea, which vibration information may be used for proactively detectinga beginning earth quake.

Temperature and light sensors may be used to provide accurate weatherinformation, and also to control smart buildings in the area.

Light sensors may be used to control street lights and other lights in aneighborhood.

In one embodiment the additional devices 810 may comprise LEDs (LightEmitting Diodes) for possible ornamentation of a structure.

In the following the operation of antenna arrangements according toherein will be discussed.

An important realization that the inventor have made is that both thetransmitter and receiver processing can be distributed under certainassumptions, such as that of FIG. 9 showing a schematic view of a UE 115communicating with antenna devices 315. A general method for executingthe processing illustrated in FIG. 9 is shown in FIG. 10 to whichsimultaneous reference is given. As seen in FIG. 9A a user equipment 115sends 1010 a pilot transmission. In response thereto a data signal touser UE 115 is transmitted 1020 using conjugate beam forming as seen inFIG. 9B, which enables the processing required to be performed perantenna device 315.

The invention also teaches a method of performing per-antenna elementprocessing in a multi-antenna transmitter (FIG. 11 ) and receiver (FIG.12 ). FIG. 13 shows a flowchart for performing the method of performingper-element processing.

Referring to FIG. 11 showing a serialized transmission TX interface ofMassive-MIMO transmission, where we note that the transmit weightcalculations is performed in a first step 1310. This can be done byinstructing each UE transmit one or more pilots that are used todetermine the transmitter side channel state information (CSI-T)required for weight calculations. For example, the transmit weights maybe selected as the conjugate of the channel estimation from the pilottransmissions. Transmit-weight calculations can be performed in manyways and they are not the primary focus of this invention. In someembodiments the transmit weight calculations are done “per element”(e.g. as the maximum ratio transmission, MRT, weight calculationdiscussed above).

On the transmitter side, see FIG. 12 showing a serialized reception RXinterface for Massive-MIMO reception, the data to transmit istransmitted 1320 on a shared data bus. Each antenna element process unitreceives 1330 up to K streams of data (either one data stream per useror one user with K data stream, or some other combination of users anddata stream resulting in K data streams in total) from the shared databus.

In each antenna element the data streams are scaled 1340 with thepre-calculated antenna weights and the sum-signal is transmitted over aradio channel to the receiver(s).

On the receiver side each antenna element processing unit receives 1350the data corresponding to the different data streams on a shared databus. The received antenna signal is multiplied with the receptionweights corresponding to the different data streams (said receptionweights are calculated in a previous training phase). The processed datastreams are combined 1360 with the received data streams from theneighboring antenna element processor unit and the resulting datastreams are encoded and transmitted 1370 on said data bus to the nextantenna processing unit.

This invention relates to making single antenna modules (possibledual-polarized) or models with smaller number of antennas elements. Wewill denote the antennas on antenna unit m as antenna element m. Eachsuch antenna unit implements channel estimation and suitable base-bandprocessing, e.g. could for multiple antennas contain advances receiverssuch as IRC and possible advanced transmitters such a zero-forcing etc.One such radio unit contains an input from a previous radio unit and anoutput to a next radio unit.

The input contains incoming data from a previous antenna unit m−1, saidincoming data contains combined signals from one or multiple previousantenna units 1, . . . , m−1 for one or more UEs. In reception theantenna unit use its SINR and channel estimate for each of said UEs toscale and phase rotate its antenna signal from antenna element m(possible from multiple antennas) and add said antenna signal to theincoming combined signals received for each of the UEs. This combinedsignal is then outputted to a next antenna unit m+1.

In transmission the radio unit receives the input data for one ormultiple UEs, for each of said UEs the radio unit scales and phaserotates the input data according to a channel estimate that the antennaunit has performed previously and adds said signals together or form atransmission signal transmitted on antenna element m. The input data isforwarded to the next radio unit.

Observe that this creates a chain of such antenna units, the sequence isstarted by an input that is empty, and it is ended by outputting thetotal sum signal to a unit configured to decoded the sum signal, orotherwise continue the processing of the signal.

The reception as well as the transmitter processing may be performed inparallel. In the receiver processing the results for each data streamneed to be added to the processing result from the previous antennaelement in the chain. The combining step is a simple per-stream additionoperation and can be performed in a few batch steps as depicted in FIG.14 showing an example of batch receiver processing. Note that antennaelements in a batch processing implementation may be located in e.g. atwo dimensional or a one-dimensional array.

In order to reduce the delay of the receiver processing it is possibleto start the processing at multiple antenna elements in parallel and dothe processing over several batches, as depicted in FIG. 14 . Theintermediate result from each batch processing step may then be combinedby a simple addition operation. Since most of the per-antenna elementprocessing can be performed without any input from other elements it ispossible to perform almost all processing in parallel. It is alsopossible to do the batch processing in several steps, i.e. by processingbatches of batches (not shown in FIG. 14 ).

Below an example embodiment of how configuration and channel estimationmay be achieved in a system as per the present invention.

In the practical implementation of the described invention, the radiounits need to obtain knowledge about the UE for which the radio unit issupposed to do processing. Hence the radio unit needs to be aware aboutthe timing of reference signal transmissions and the timing when data issupposed to be transmitted. The clock interface as depicted in FIG. 11and FIG. 12 is important to achieve coherent reciprocity as this enablesthe units to synchronize to a common clock. In the configuration stepswe can schematically see the order among the events needed fortransmission in FIG. 15 , showing an example of a configuration ofreference signal for reciprocity based transmission, and reception inFIG. 16 showing an example of a configuration of reception of an ULtransmission. The schematics should be viewed as an example, forexample, the channel estimation could be performed after the receptionof the configuration of the transmission of sk in FIG. 15 . Observe thatthe signaling from the control unit to a radio unit is typically relayedthrough a set of other radio units, in the same principal as when thetransmit signal is relayed by forwarding the configuration data packet.

It should be noted that since FIGS. 15 and 16 show a time line or timediagram, they may be regarded as flowcharts for illustrating a method.

Below an example embodiment of how weighted conjugate beamforming may beachieved according to an invention disclosed herein. It should be notedthat even though the manner is taught with reference 4 to be used in adistributed massive MIMO system 600 as disclosed herein it may be usedwith antenna arrangements 300 as disclosed herein, but also withtraditional antenna arrangements.

As mentioned in the background section, channel hardening property isless pronounced in D-maMIMO because of its network topology, resultingin worse system capacity. Therefore, within this invention, we alsopropose a proper precoding technique to boost the channel hardening atthe user side in such a scenario, named as weighted conjugatebeamforming (WCB). Compared to the conventional precoding scheme adoptedfor D-maMIMO, that is conjugate beamforming scheme (CB), also known asmaximum ratio transmission (MRT), WCB precoding technique performs aweighted phase-shift of the transmitted signal. Analytically speaking,let M, K be the number of APs and UEs respectively, q_k be the datasymbol intended for the k-th UE, and g mk be the channel coefficientbetween the m-th AP and the k-th UE, then the transmitted data signalfrom the m-th AP to all the UEs can be written as

$x_{m}^{WCB} = {\sum\limits_{k = 1}^{K}{\frac{g_{mk}^{*}}{{g_{mk}}^{\alpha}}{q_{k}.}}}$

where the superscript ( )* stands for conjugate, α is defined asbeamforming weight, and α≥0. The ratio g*_(mk)/|g_(mk)|^(α) representsthe so called precoding factor, for the WCB scheme. By contrast, for CBthe precoding factor is g*_(mk). Therefore, CB is a special case of WCB,i.e., when α=0.

By increasing α value, the farther an AP from a given user is, the morepower it transmits to that given user. Therefore, the number of APseffectively involved in coherently serving a given user increases,resulting in higher degree of channel hardening. On the other hand, fromthe AP perspective, increasing the number of UE to be served leads tosparser power allocation and, as a consequence, lower per-user SINR,since the overall transmit power is shared among more active users. Thisrepresents a trade-off and the optimal value of the beamforming weightα, that maximizes system performance in terms of per-user achievabledownlink rate, can be computed by solving the following optimizationproblem,

${\max\limits_{\alpha}\mspace{14mu} R_{k}} = {\log_{2}\left\lbrack {1 + {{SINR}_{k}(\alpha)}} \right\rbrack}$s.t.  α ≥ 0,

where R_k is the achievable DL rate of the k-th UE, and SINR_k is theeffective SINR at the k-th UE, which depends also from a.

Next, we introduce a simple example to show the benefits provided by oursolution with respect the state-of-the-art. Let us consider a D-maMIMOsystem where a BS equipped by M APs simultaneously serves Ksingle-antenna UEs (M>K), in the same frequency band, by operating inTDD mode. Simulations aim to compare the performance, in terms ofper-user achievable DL rate, obtained by using our solution and theexisting solution of the state-of-the-art. The main simulationparameters are listed below.

PARAMETER VALUE M 100 K  20 Simulation area 1 km² Coherence Interval 200symbols Carrier Frequency 2 GHz Bandwidth 20 MHz Small-scale fadingmodel Block Rayleigh fading with i.i.d realizations Large-scale fadingmodel three-slope pathloss model + uncorrelated shadow fading withstandard deviation 8 dB Antenna height 5 m UE antenna height 1.65 mRadiated power 200 mW DL, 100 mW UL.

FIG. 17 shows the 10th percentile, median and 90th percentile of theper-user achievable downlink rates, for different values of α, where itcan be seen that When α=0, WCB corresponds to CB. The rates provided bythe reference scheme (CB), corresponding to α=0, are equal to 1.3, 1.83,2.34 bits/s/Hz respectively. As we can see, this rates can be furtherimproved by adopting the proposed scheme (WCB), i.e., taking α>0.Moreover, the concave shape of the curve highlights the trade-offmentioned earlier: the more APs are involved in a coherent transmission,the better the channel hardening is, but the worse the per-user SINR is.By adopting WCB with α=0.8, the maximum 10th percentile per-user DL ratecan be achieved by the system, i.e., 1.57 bits/s/Hz, corresponding to animprovement of about 21% over the CB scheme. Similarly, by adopting WCBwith α=1.2, the maximum median per-user DL rate achieved by the systemis 2.58 bits/s/Hz, corresponding to an improvement of about 41% over theCB scheme. In terms of 90th percentile rate, the gain over the referencescheme is about 53%, by choosing α=1.4.

Finally, we proved that WCB can outperform the CB scheme by properlychoose the beamforming weight α. The WCB precoding scheme hardens theeffective channel gains at the users, and, as a consequence, reduces theso-called user beamforming uncertainty gain, which comes from the user'lack of the short-term CSI knowledge. Therefore, the users can reliablydecode the downlink data using only long-term statistical CSI. Thispotentially makes downlink training unnecessary, resulting in bettersystem sum-capacity, resource allocation and system scalability.

FIG. 18 shows an example where a long range interface is used to connectone or more antenna arrangements to a base station. Using a combinationof long range interfaces and short range interfaces has the benefit ofenabling for a larger data speed over larger distances using cheapermaterial. One example, is to use fiber optics or 10 GB Ethernet for thelong range interface and electrical and analogue compionents for theshort range interface.

FIG. 18 also shows how antenna arrangements can be divided into subarrangements each having a distributed processing central (DPU) forperforming some of the computations for the sub arrangement, such ascollating partial processing results from or to the antenna devices.

FIG. 19 shows an example embodiment of the present invention wherein aseries of antenna sub arrangements are shown having distributedprocessing units 1903.

In order to maintain an exact synchronization, each sub antennaarrangement may comprise a local clock oscillator 1902 as transmittingmany different signals with perfect phase alignment requires veryaccurate time synchronization.

This can be achieved by the distributed local clock circuits(oscillators) along the length of the antenna arrangement, each localclock being synchronized to a central clock reference.

When deriving a time reference for distributed processing in adistributed processing unit the time delay (phase shift) between theelements (caused by signal propagation delay in the cable) may becalibrated and compensated for.

As is known, the radio frequency waves, being electromagnetic waves,propagate from (and to) an antenna in a given polarization plane. Theefficiency at which a signal is received thus depend on at which anglethe receiver is being held in relation to the sender. To enable for amore uniform reception that is relatively insensitive to the angle ordirection that a device is being held at, common practice has become totransmit signals as cross-polarized signals. This requires that twoantennas are arranged substantially orthogonally and to transmit thesame signal simultaneously. A signal will then always be received at anacceptable signal strength level irrespective the angle of the receiver.

One problem with such radio stripes is that for dual-polarized antennasthe required width of the radio stripe increases with decreasingfrequency. The width of an antenna stripe is small for high frequenciesbut it can be prohibitively large for lower frequencies.

The inventors have realized, after inventive and insightful reasoning,that by going against fundamental principles in radio frequencytransmissions, a smaller and more flexible antenna arrangement may beachieved.

In one embodiment, the inventors are proposing to simply step away fromthe orthogonal arrangement and arrange the antennas in a non-orthogonalarrangement by changing the angles between the antennas. The drawback ofthis is that at some angles corresponding to the directions where theangle between the antennas are greater than 90 degrees, the signal willbe received at a lower signal level (and hence quality). However, as theinventors have realized, the sheer number of antennas being used in anarrangement as per the teachings herein and taken into account that allantennas will most likely not be arranged in the same direction as inprevious MIMO arrangements, will compensate for the loss of efficiencystemming from each individual antenna, and the overall efficiency willremain acceptable. FIG. 20 shows an example where the antennas arearranged in a non-orthogonal co-polarized manner. Even though theantennas are not strictly cross-polarized they are still co-polarized inthat they may be received at an amplitude in each direction, although insome directions (corresponding to the wider angle between the antennas)the signal level will be lower than in directions corresponding to thenarrower angle between the antennas.

As can be seen, the sum of the corresponding angles between the antennasequals 180 degrees and in one embodiment, one angle is 45 degrees, 50degrees, 55 degrees, 60 degrees, 65 degrees, 70 degrees, 75 degrees, 80degrees, or 85 degrees.

As can be seen, this enables the antenna to be made thinner in onedirection, which makes the antenna easier to attach to differentstructures. The greater the step away from 90 degrees, the greater theeffect in reducing the width of the antenna.

In one such embodiment, the antennas are arranged so that the polarityof one antenna is opposite the polarity of the next antenna. This willfurther even out the polarization losses from each individual antenna.This also leads to a simpler arrangement of the antennas. FIG. 21 showsa schematic view of such an arrangement.

In one embodiment, the inventors are proposing an alternative oradditional manner of how to step away from the orthogonal arrangementand arrange the antennas in a non-orthogonal arrangement by distortingthe antennas. The drawback of this is that the signals will bedistorted, but still be cross polarized. However, as the inventors haverealized, the sheer number of antennas being used in an arrangement asper the teachings herein and taken into account that all antennas willmost likely not be arranged in the same direction as in previous MIMOarrangements, will compensate for the loss of efficiency stemming fromeach individual antenna, and the overall efficiency will remainacceptable. FIG. 22 shows an example where the antennas are arranged ina non-orthogonal manner.

In one embodiment, the reducing of the angle between the antennas andthe distortion of the antenna may be combined. FIG. 23 shows such anarrangement.

In lower frequencies (less than ˜5 GHz) the width of the stripe expandsand may be impractical to deploy. (˜decrease simplicity).

The target of invention is to keep the radio stripe width (w) onpractical levels for low frequencies (e.g. <5 GHz). Two principlesolutions for this are depicted in FIGS. 20 and 21 (showing onealternative) and FIG. 22 showing another alternative. In FIGS. 20 and 21the two antenna elements associated with the two polarization branchesare installed with an angle between the elements (α) less than 90degrees.

From linear algebra we know that any pair of two-dimensional vectorsthat are not lineary dependent can form basis-functions for that vectorspace. These two basis-function that can then be used to represent anyother vector in the plane as a linear combination of the two basisfunctions.

As an intuitive explanation to why this works we expand on“basis-functions”. In mathematics, a set of elements (vectors) in avector space V is called a basis, or a set of basis vectors, if thevectors are linearly independent and every vector in the vector space isa linear combination of this set. In more general terms, a basis is alinearly independent spanning set. Given a basis of a vector space V,every element of V can be expressed uniquely as a linear combination ofbasis vectors, whose coefficients are referred to as vector coordinatesor components. A vector space can have several distinct sets of basisvectors; however each such set has the same number of elements, withthis number being the dimension of the vector space.

As long as the polarization branches in an antenna are not lineardependent (i.e. not completely parallel) they can still be viewed asbasis-functions. They do not have to be orthogonal, although this is adesired feature. Using non-orthogonal polarization branches we may stillhave a channel the same high rank as before, although in a less spaceconsuming format. The drawback with this arrangement is that the twopolarizations are correlated and that this will result in that not allchannel dimensions are equally strong and useful. But in general, havingaccess to two correlated antenna polarizations is much better than toonly have one single antenna polarization.

By applying a non-orthogonal cross shape the stripe-width (w_(stripe))can be adjusted. With a “slanted” cross polarized antenna arrangement(FIGS. 20 and 21 ) the required radio stripe width becomes

$w_{stripe} = {\frac{\lambda}{2}{\sin\left( \frac{\alpha}{2} \right)}}$

Note that a in the above equation is the angle indicated in the figuresand not the beamforming weight mentioned above. λ/2 is the length ofeach antenna element of the cross-polarized antenna arrangement, where λis the (approximate) wavelength of signals to be transmitted. As isshown in FIG. 22 one may also “bend the edges” of the antenna elements,while keeping the angle in the center of the cross equal to 90 degrees.This will have essentially the same effect, i.e. it will create acorrelation between the antenna polarization branches.

As is shown in FIG. 23 , altering the angle as well as “bending theedges” may also be done in combination.

Polarization antenna distortion can be used to enable compact radiostripes supporting multiple frequency bands in a wide range. Forexample, only the antennas used for the lowest frequency band usesdistorted polarization antenna elements. Note that for very highfrequency bands the antenna elements become so small that several pairsof cross polarized elements can fit within a small stripe bandwidth. Onesuch example is shown in FIG. 24 where an antenna arrangement, anantenna stripe, comprises a plurality of antenna elements 2410, 2420 and2430, As is indicated the antenna elements may be more than illustratedand may also be arranged in different groupings, the example of FIG. 24only being one variation possible out of many. In this example, theantenna strip comprises a plurality of mid-frequency band antennaelements 2410 (for example 15 GHz) with uncorrelated dual-polarizationantennas, arranged without being stacked. In this example, the antennastrip also comprises a plurality of low frequency band antenna elements2420 (for example 2 GHz) with correlated dual-polarization antennas,arranged without being stacked. In this example, the antenna strip alsocomprises a plurality of high frequency band antenna elements 2430 (forexample 60 GHz) with uncorrelated dual-polarization antennas, arrangedvertically stacked.

In one embodiment, as shown in FIG. 25 , antenna arrangement of FIG. 24being a multi-band capable radio-stripe, is used to implement relays forcovering of black-spots. The low-frequency band is suitable for longrange and/or wall penetrating back-haul links to (larger) antennaarrangements, while the higher frequency band may be used for access tothe UEs. This kind of simple “tape-up” installation of relays may be aninteresting solution in several different deployments

Reference has been made herein to various embodiments. However, a personskilled in the art would recognize numerous variations to the describedembodiments that would still fall within the scope of the claims. Forexample, the method embodiments described herein describes examplemethods through method steps being performed in a certain order.However, it is recognized that these sequences of events may take placein another order without departing from the scope of the claims.Furthermore, some method steps may be performed in parallel even thoughthey have been described as being performed in sequence.

In the same manner, it should be noted that in the description ofembodiments, the partition of functional blocks into particular units isby no means limiting. Contrarily, these partitions are merely examples.Functional blocks described herein as one unit may be split into two ormore units. In the same manner, functional blocks that are describedherein as being implemented as two or more units may be implemented as asingle unit without departing from the scope of the claims.

Hence, it should be understood that the details of the describedembodiments are merely for illustrative purpose and by no meanslimiting. Instead, all variations that fall within the range of theclaims are intended to be embraced therein.

The invention claimed is:
 1. An antenna arrangement comprising a bodycomprising a plurality of antenna devices arranged in one row, the bodyhaving a flexible structure and an elongated shape and at least one ofthe antenna devices comprises an antenna pair arranged non-orthogonallyin a co-polarizing manner.
 2. The antenna arrangement according to claim1, wherein each antenna pair is arranged non-orthogonally by beingarranged at angles not being straight with relation to one another. 3.The antenna arrangement according to claim 1, wherein each antenna pairis arranged non-orthogonally by being at least one antenna of theantenna pair being arranged in a bent or not straight form.
 4. Theantenna arrangement according to claim 1, wherein the antennaarrangement comprises at least two antenna pairs, where the antennapairs are arranged so that the polarity of one antenna pair is oppositethe polarity of an adjacent antenna pair.
 5. The antenna arrangementaccording to claim 1, further comprising a connector for connecting theantenna arrangement to a central unit, acting as a base station.
 6. Theantenna arrangement according to claim 5, further comprising a busportion and a power supply line for transmitting data to and from theplurality of antenna devices and/or to/from the central unit.
 7. Theantenna arrangement according to claim 6, wherein the bus portion andthe power supply line are the same connection.
 8. The antennaarrangement according to claim 1, wherein each antenna device comprisesa controller (CPU) and an antenna element (ANT), wherein said controller(CPU) is configured to perform per element processing, the antennaarrangement thus being arranged for distributed processing utilizing thecontrollers (CPU) of the antenna devices.
 9. The antenna arrangementaccording to claim 1, further comprising or being arranged to beconnected to a connector for connecting the antenna arrangement to atleast one other antenna arrangement.
 10. The antenna arrangementaccording to claim 9, further comprising or being arranged to beconnected to a power unit.
 11. The antenna arrangement according toclaim 1, wherein at least a majority of the antenna devices are arrangedto face the same direction.
 12. The antenna arrangement according toclaim 1, further comprising at least one additional device.
 13. Theantenna arrangement according to claim 1, wherein the antenna devicesare arranged in a cover or sheath of said body.
 14. The antennaarrangement according to claim 1, wherein the body is a cable.
 15. Theantenna arrangement according to claim 1, wherein the body is anelongated strip.
 16. The antenna arrangement according to claim 1,wherein the body is a film.
 17. A distributed massive MIMO (MultipleInput Multiple Output) system comprising a central unit arranged to actas a base station and at least one antenna arrangement comprising aplurality of antenna devices, the body having a flexible structure andan elongated shape and at least one of the antenna devices comprises anantenna pair arranged non-orthogonally in a co-polarizing manner. 18.The distributed massive MIMO system of claim 17, further comprising anantenna panel.